Although the Moscow demo[0] look better (in my eyes) in jxl than wepb.
Note also that JXL is still being worked on. We have no information also about which encoder was used (I am assuming the reference encoder, since it is the only one that I know off right now) and which version.
Edit: the Citroën demo is also a clear win for JXL.
The singer’s left hand has wrinkles in the original image that disappear in WebP2.
Overall, WebP2 and especially AVIF are really good at very low bitrates (<1 bit per pixel), but unlike video, images on the Web will always be shown at the smallest bitrate necessary to be indistinguishable from the original; there, JXL tends to show all the details at a lower bitrate.
Note also that JXL is still being worked on. We have no information also about which encoder was used (I am assuming the reference encoder, since it is the only one that I know off right now) and which version.
Edit: the Citroën demo is also a clear win for JXL.
[0] https://eclipseo.github.io/image-comparison-web/#moscow&WEBP...